Sheet metal forming mechanism



March 20, 1951 TAYLOR 2,545,904

SHEET METAL FORMING MECHANISM Filed Oct. 21, 1948 Jnventor Dana/d 2. fiy/or' v M attoine Patented Mar. 20, 1951 UNITED STATES PATENT oFFl cef-Q SHEET METAL FORMING MECHANISM Donald R. Taylor, Tullos, La.

Application October 21, 1948, Serial No. 55,709

I 1 Claim.

My invention relates to a sheet metal formin mechanism of the type used particularly in the repair of automobile bodies and consists in certain improvements on similar prior art mechanisms.

Prior art mechanisms of this type are provided with a C-shapedyoke, from one side of the opening of which yoke an air driven hammer is extended to operate on an anvil member called a dolly extended upwardly from the other side of the yokes opening. Such an arrangement permits an operator when repairing an automobile fender, for instance, to position the bent portion of the fender into the yoke between the air driven hammer and the dolly and to move the metal forming mechanism about over the fender resting on the dolly while the hammer is in operation to reshape the bent metal to its original contour.

After considerable use of prior art metal forming mechanisms constructed according to the description set forth above, it was found that the results obtained were highly unsatisfactory, among other reasons due to the lack of ready adjustment of the effective hammer blows on the metal material M rested on the dolly.

In the prior art metal forming mechanisms the hammer in its retracted position should be set in an adjusted position of approximately /32 of an inch above the lower surface of a bell guide which is rested on the piece of sheet metal being worked on. The bell guide steadies the hammer so that the ram of the hammer strikes a square blow on the sheet metal being worked on. In these prior art hammers only the first adjustment of /32 of an inch clearance between the lower face of the ram in its retracted position and the lower face of the bell guide is made and is maintained for all classes of work performed by the hammer regardless of the curvature of the sheet metal surface being worked on by the hammer.

The main object of the present invention is to provide a sheet metal forming mechanism which is an improvement on the prior art type sheet metal forming mechanisms above described such as is disclosed in Patent No. 2,148,619, which improved sheet metal formingmechanism is provided with a secondary adjusting means for the bell guide member. By means of this secondary bell guide adjusting means, the operator of the hammer may raise or lower the bell guide during an operation of the hammer in order to exert pressure through means of the bell guide on the sheet metal specimen being worked on to assist in the shaping thereof.

Another object of this invention is to provide I a ram shoe for use with the ram'member of prior art sheet metal forming mechanisms by means of which ram shoe the metal being worked 2 f on is clamped down on the dolly member of the mechanism. and by means of which ram shoe the force of the ram blows isspread over awider surface than the bottom surface of the ram headl Another object of this invention is to provide in a metal forming mechanism of the prior art type above described a ram shoe used for spreading the force of the ram blows and with the further provision of a spacing means for lowering the ram shoe to lengthen slightly the travel of the ram to increase the striking force of the ram on the ram shoe.

Another object of this invention is to' provide in a sheet metal forming mechanism of the class above described a ram shoe which the ram of the mechanism is adapted to strik and which ram shoe is positioned under a downwardly adjustable member of the mechanism to be'moved by the same to clamp' a sheet metal member against the dolly and wherein pressure may be applied to the sheet metal member to assist" the action of the hammer in the forming of the sheet metal member. 7

Other objects and advantages of this invention will be found in the following detailed descri'p-- tion of the mechanism shown in the accompanying drawings in which:

Figure 1 is a partially broken assembly view of a device embodying my invention in a sheet" metal forming mechanism;

Fig. 2 is a side elevational view ofthe metal forming mechanism;

Fig. 3 is an enlarged, broken sectional view through the air hammer and the dolly assembly portion of the metal forming mechanism;

Fig. 4 is a broken View showing the metal forming mechanism being used on a concavesur face; and

Fig. 5 is an exploded view of an assembly of some of the members of the sheet metal forming mechanism illustrated in Fig. 3 of the drawings. In the drawings, numeral l0 designates an air cylinder provided with an upset upper end having a coarse male thread thereon threadedly engaged in'an upper collar II'. This collar H is split down one side and provided with a threaded squeeze pin I2 of prior art design which binds the cylinder ID in tight threaded engagement with the collar l l to prevent anymovementof the cylinder l0 due to the jarring action caused by the tool in operation. Y

The upper collar H is also provided with a hollow, open side port l3 adapted to receive the upper end of the C shaped yoke 14. The'side wall of this port I3 is also split and provided with inder I0 is an air hose adapter l6 provided with.

a swivel collar I1 and the usual air connection fittings l8 connected with a source of compressed air not shown.

The lower end of the cylinder ID is provided with a portion of much finer thread 19 than on the upper end of the cylinder I0. These fine threads l9 are threadedly engaged by an extended bell guide 20 the lower face 2| of which is surfaced in a perfect right-angular plane with the vertical axis of the cylinder Hi. Above the bell guide 20 in threaded engagement with the fine thread I9 is a split lock nut 28 having a squeeze pin 29 of prior art design for clamping the lock nut 28 to prevent the bell guide 20 from moving upwards from its adjusted position against the metal being worked on.

The ram 22 is provided with an upwardly extending shank which is releasably fitted into the bre'23 of the cylinder l 0, the upper end of which terminates below a piston, not shown, in the cylinder Ill. The piston strikes the head of the ram 22 and drives it down against the upper surface of the ram shoe 24 clamped on the sheet of material M being shaped. The rain 22 is provided with a retaining ring, not shown, to hold it in the cylinder bore. This ring is designed to have frictional engagement with ram 22 and the bore of cylinder [0. The cylinder H3 is provided with the necessary ports and by -passes, not shown, to make the piston reciprocate in the cylinder is. The action of the air hammer itself is-not shown on the drawings, since it forms no part of the present invention.

It should be explained, however, that in this type of metal forming mechanism the ram is not connected directly to the piston of the air hammer, but is struck by the piston in its downward stroke. The ram 22 bounces backwardly into position to be struck again by the piston. The ram 22 employed in the illustrated sheet metal forming mechanism may be operated with or without the ram shoe 24.

It will'be remembered that in the device on which the present improvements have been made the ram 22 has a very short stroke and to operate efiiciently must be placed in an adjusted position with its lower face approximately of an inch away from the lower face of the bell guide 20 if the maximum pressure is to be obtained.

In order to maintain the maximum pressure and stroke of the ram 22 and still be able to give the necessary adjustment for various thicknesses of material, I have provided a removable cup washer 30 having a central hole 3| whereby the same may be mounted on the upper rim of the ram shoe 24 under which cup washer any number of washer-like shims 32 may be used as desired to lower or raise the striking face of the head of the ram 22 toward or away from the ram shoe 24. Parts 30 and 32 are designed to frictionally' receive the ram 22 and normally maintain the ram shoe 24 in assembled relation with ram 22. Thus theefiecti've stroke of the ram 22 may be adjusted to meet the condition of the material being worked on 'whiie'the piston stroke is maintained without variation. But since the overall travel of the ram 22 is varied, its striking force is varied.

The lower end 34 of the C-shaped yoke I4 is bored out to receive a tightly pressed,-hardened bushing 25 in which is removably mounted the shank portion 26 of the dolly 21. The dolly 2'! may be made many shape desired and according to the type of work it is best adapted to perform. For instance, if it is required to flatten out a piece ofsheet metal, adolly would be used which would be circular in cross section having a fiat upper face at right-angles to the shank axis. Since both the dolly 21 and the ram shoe 24 are removable, it is readily apparent that the working faces of the two could be matched to suit various contours of sheet metal members.

It can now be seen that the tool is extremely versatile and that the various contours of automobile bodies may be straightened with power rather than by the slow manual process heretofore known.

As hereinbefore stated, in a device constructed according to the teachings of the metal forming mechanism of prior art construction being improved upon in this invention, the ram 22 must be set or adjusted to make a stroke of a; of an inch above'the lower contacting faced the bell guide 20 for the machine to perform efficiently. This particular setting, however, may or may not be the proper setting for all thicknesses of material worked on.

When the material was thin, the ram member of prior art type metal forming mechanisms had a tendency to stretch the metal by flattening it below its original thickness. Such was the result in one instance where an automobile top was being repaired. When the damaged spot had been worked on, it was found that th portion of metal worked on had been so stretched that it was entirely tooexpanded to conform to its proper place in the contour of the top. An entirely new automobile top had to be purchased.

In Fig. 4 of the drawing, it will be seen that I have provided a dolly 2'! having a diameter smaller than the inside diameter of the bell guide 26. With such an arrangement an operator is able to place the sheet metal forming mechanism in an operating position over an indentation in a piece of sheet metal and, due to the fine threads provided on the lower end of the air cylinder I0, he is enabled by means of a downward advance of thebell guide 20 to bend the metal into an upward curve as shown in Fig; 4. A great portion of the indentation can be raised by merely moving the bell guide 20. With the air hammer operating, the operator may lower the bell guide 20 or may raise it to a normal setting against the upper lock nut 28 in which setting the lower surface of the bell housing 20 is in the plane of the lower surface of the ram shoe 24.

From the above description of my improvements in sheet metal forming mechanisms, itis readily apparent that versatility of operation and ready adjustment in a device of this type cannot be overemphasi'zed due to the uneven contours in modern sheet metal designs.

An operator may use my improved sheet metal forming mechanism successfully even without the bell guide 20 because the metal M may be clamped between the ram shoe 24 and the dolly 21. With this arrangement of the mechanism, an operator can work up closer to a beaded edge or rightangularly flanged edge of "a metal specimen M than would be possible of accomplishment in using theprior art type of sheet metal forming mechanism because the bell guide member is essential to its successful operation and which bell guide would space the ram of the prior art mechanism inwardly of the beaded edge or rightangularly flanged edge of a metal specimen being worked on.

My improved metal forming mechanism puts the bell guide 20 to a use in forming the metal specimen M which is a new use of such a memher not contemplated by-the prior art.

It is further pointed out that by incorporating the novel member, the ram shoe 24, the ram head 22 can never have a chance to strike a sheet metal specimen M being worked on in an angularly directed blow, which under prior art practice would make a nick in the metal specimen M. The ram shoe 24 furthermore acts as a means of spreading the applied force of the ram 22. It is further pointed out that by means of the cup washer 30 and the shims 32 the ram shoe 24 may be spaced to or from the striking face of the ram 22 by means of which spacings the effective blows transmitted by the ram 22 through the medium of the ram shoe 24 and thence to the metal specimen M resting on the dolly 2'! may be varied to suit the operator. This feature of this improved sheet metal forming mechanism has been found to be of great value to a metal worker who uses the same metal forming mechanism on sheet metal specimens M of widely varying thicknesses. By means of the number of shims 32 the operator uses, the effective blows of the ram 22 are adjusted as dictated by the thickness of the metal specimen M. It is pointed out that this simple adjustment may be easily made without the operators having to make any other adjustments in the sheet metal forming mechanism.

While I have described my invention in detail, it is to be understood that many different designs of ram shoes 24 may be used within the scope of this invention to suit the various conditions met with in sheet metal work as to thicknesses of the material and as to the curvatures of the sheet metal specimens M.

Having ,thus described my invention, I claim:

A sheet metal forming mechanism comprising a yoke shaped frame, a hammer casing having a power hammer therein adjustably mounted in one end of said yoke frame for movement in a direction normal thereto and extending crosswise of the opening of said yoke frame, means for locking said hammer casing in adjusted positions in said yoke frame, a dolly mounted on the other end of said yoke frame and extended normally inwardly from the same in a position opposite to said power hammer to cooperate therewith in the shaping of sheet metal or the like, said power hammer provided with a slidably mounted ram extended out of the inward end of said casing, a ram shoe provided with a recess in which said ram reciprocates for striking said ram shoe, whereby said ram shoe imparts blows to the sheet metal surface positioned between said ram shoe and said dolly, said ram shoe being provided with a cylindrical upstanding wall portion encircling said ram, the upper edge of said cylindrical portion being positioned directly beneath the lower surface of said hammer casing whereby said shoe may be brought into pressure contact with said metal surface by lowering said hammer casing and wherein said ram shoe is provided with a spacing means for extending the same away from said ram, said spacing means comprising a cupshaped washer adapted to slidably fit on the upper rim surface of said cylindrical portion of said ram shoe, and annular shim means interposed between said cup-shaped washer and the upper surface of said cylindrical portion.

DONALD .R. TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,148,619 Hanschild Feb. 28, 1939 2,260,624 Johann Oct. 28, 1941 2,263,423 Kattrein Nov. 18, 1941 

